Adam wrote the original PDL specification in February, 1995. PDL work commenced upon acceptance shortly thereafter, so the period from mid-1995 to the end of 1998 marks the development of the PDL1 to PDL4 boards and associated firmware and software. PDL1 boards were first produced in late '96, here are the films from September, 1996.

Many different configurations were built, some had a third transmitter for casing / line sensing, some were hybrids being housed in the old PLED SS cylinder.